“The manuscript ‘Car safety seats for children: rear facing for best protection’ was published in Injury Prevention in 2007, after peer review. The paper used U.S. data from the National Automotive Sampling System Crashworthiness Data System to conclude that children 0–23 months were less likely to be severely injured when using a rear-facing car seat than a front-facing car seat. This result, along with similar data from Swedish experience and biomechanical studies, has been used as the basis for public education and policy recommendations that favor a rear-facing position for children under age two in car seats.
In 2016, the journal was contacted by a biostatistician employed as an expert witness in a court case involving a car seat manufacturer. She indicated that she was unable to replicate the results of the analysis reported in the Henary et al paper. Despite requests from the editor, she did not provide details of her analysis nor did she submit a manuscript describing her analysis, her results, or their implications.
The same letter was also forwarded to authors of the Henary et al study. They, and colleagues, have communicated to the journal that their attempts to replicate the analysis also fell short. Specifically, they believe that survey weights were improperly handled in the initial analysis, which caused the apparent sample size to be larger than the actual sample size. This resulted in inflated statistical significance. It is important to stress—per the authors—there is no evidence that current recommendations are harmful. However, these field data are inadequate to statistically support the safety benefit of rear-facing seats.
The journal has asked the authors to provide an erratum, correcting the analysis and results. We anticipate receiving this soon. We have also offered to publish updated analyses based on more recent data. In the meantime, we are releasing this statement of concern to alert readers and policymakers to uncertainty about the weight and significance of the findings reported herein.”Reference: Henary B.; Sherwood C.P.; Crandall J.R.; et al. “Car Safety Seats for Children: Rear Facing for Best Protection.” Injury Prevention. 2007. 13:398–402.

Re-evaluating Car Seat Orientation and Safety

Published: SRN July/August, 2017. Updates will be posted here as they become available.

Over the past year, certain developments have caused some CPS advocates to be concerned and/or confused about the relative safety of children riding rear facing versus forward facing. Testimony in a recent lawsuit that questioned the benefits of extended RF, changes to RF and FF requirements in CR instructions, and updated state laws have all contributed to the confusion. Most recently, an expression of concern published by Injury Prevention and an online statement (see sidebar, left) posted by the CR manufacturer Dorel have understandably raised many questions among CPSTs. The following describes these developments and gives additional context to help CPSTs make sense of recent news.

The Evolution to Extended RF
As recently as the early 1990s, in the U.S. and Canada babies as young as 6 months old were routinely turned to face forward, due partly to lack of awareness of the benefits of riding rear facing and also the scarcity of CRs designed to be safely used longer in the rear-facing mode.
Today, this situation has changed dramatically. Over the years, organizations like NHTSA, CR manufacturers, and industry research groups have conducted extensive lab testing that has shown the safety benefits of placing babies and small children rear facing in the car, and real-life experience in Sweden, where riding RF past age 2 is the norm, consistently supports this, as well. CPSTs have done a tremendous job educating the public on this subject, and CR manufacturers have filled the market with models allowing extended RF capacity. Babies under age 1 are now far less frequently placed forward facing, and many parents heed the AAP’s best-practice advice to keep children rear facing until at least age 2.

AAP and NHTSA Guide U.S. CPS Policy
These behavioral and product changes were supported and prompted by CPS best-practice policy.
In 1996, the American Academy of Pediatrics (AAP) first recommended children ride facing the rear until they weighed at least 20 pounds and reached 1 year of age, in order to reduce the risk of cervical spine injury in a crash. It encouraged parents of children who weighed 20 pounds prior to their first birthday to seek a CR with a higher RF usage weight (though, at the time, such CRs were rare).
By the early 2000s, there was far greater availability of CRs designed to fit and safely transport most infants up to and even over age 1. Therefore, in 2002, when the AAP updated its policy, it added that children should remain rear facing as long as possible—even beyond age 1— if the CR’s usage limits were still met. (Current Canadian policy aligns with these recommendations.)
In 2007, researchers analyzing injuries to children up to age 2 in both fatal and nonfatal police-reported crashes published an important study about this real-life data. It stated that, among children in the study group ages 12 to 24 months, those that were seated rear facing were significantly safer than forward-facing children—as much as five times safer (Henary, et al, 2007). When the AAP next revised its policy on CR selection guidelines in 2011, the committee strengthened its encouragement to keep infants and toddlers riding rear facing as long as possible, adding that best practice should be to keep infants up to age 2 rear facing unless they’d reached the highest weight or height allowed for the CR by the manufacturer. NHTSA simultaneously updated its own guidelines in 2011, agreeing that children should ride rear facing as long as possible. Although NHTSA didn’t opt to specify age 2 as a rear-facing goal, its online guidance suggests that children should remain rear facing until at least age 1 and up to as old as age 3, depending on circumstances like the CR use limits and the child’s size. (One such instance is found in NHTSA’s “Car Seat by Child’s Age and Size” chart at Parents Central on the safercar.gov website.)
Today, the 2011 recommendations from the AAP and NHTSA still guide CPS policy. Besides advising pediatrictians and caregivers, these policies have been used to develop CPS curricula, influence some enhanced state laws, and prompt instructions from CR manufacturers.

A Tragedy Spurs Re-evaluation of Evidence About Rear-Facing Benefits
Although the way children ride and the protectiveness of the CRs and vehicles they use has changed dramatically since the 2007 Henary study (the only published study to date that compares the effectiveness of RF and FF CRs using actual U.S. crash data), it took a tragedy to spur an updated study.
In 2013, a 20-month-old boy riding forward facing in a Cosco Summit combination CR was severely injured in a crash. Because the boy was four months shy of age 2, this event prompted a lawsuit against Cosco’s parent company, Dorel. The prosecution argued that the manufacturer’s instructions unsafely allowed the child to ride in the forward-facing-only CR after age 1, despite the fact that established best practice is for children to ride rear facing until at least age 2. (See SRN July/August 2016.)
In preparing a defense for the 2016 trial, Dorel hired a statistical research group, JP Research, Inc., owned by statistician Jeya Padmanaban. By that time, the data used in the 2007 Henary study was over 10 years old (spanning 1998 through 2003), so Dorel asked JP Research to replicate the study and also update it to include more recent data (2004–2014).
The results were a surprise. Using exactly the same sample set as the 2007 study, JP Research was not able to replicate the Henary results using any standard statistical methodology. In fact, its findings, presented as expert testimony in the court case, were that children over age 1 were actually safer riding forward facing than rear facing. (It is important to note that this study has yet to be peer-reviewed for accuracy; see next section.)
As expert testiomony, the contradictory study did not sway the jury, however, and Dorel lost the court case. A source at Dorel has told SRN that the company does not intend to appeal the decision, and its follow-up efforts to investigate these study findings are not motivated by litigation.

JP Research Findings, Post-Trial
The significance of JP Research’s findings clearly extends beyond one trial. JP Research is a credible firm, but the value of its study would be vastly increased by publication, which would confirm it had been thoroughly peer-reviewed for accuracy. The study has, however, been accepted for presentation in November at the Stapp Car Crash Conference, which will involve some form of peer review.
Even prior to peer review, NHTSA has been apprised of the JP Research analysis of the Henary study. On January 31, 2017, JP Research staff met with NHTSA and other key industry stakeholders in Washington, D.C., to present the findings, including speculation of potential flaws in the earlier research methodology. So it is certain that this situation is known to policymakers.
The research has also prompted changes at Dorel. In an online statement, Dorel has explained that it is the JP Research study that influenced the company to discontinue phasing in instructions that would have required children to be age 2 before riding forward facing in its Safety 1st, Cosco, Eddie Bauer, or Maxi-Cosi convertible or all-in-one CRs.
However, despite already having some influence on the industry, the fact that, to date, the study has not been peer-reviewed or made available to read in full severely curtails its usefulness for future decision-making. Although Dorel has already cited some of the study’s findings publicly, the scientific community does not consider it appropriate to do so until a work has been properly vetted. Therefore, SRN will report more fully on findings of the JP Research study when and if it is peer-reviewed for acceptance by the scientific community.

Other Research Efforts
While any updated research will carry more weight once it’s been peer-reviewed and published—as none at press time has—this situation is nonetheless firmly on the radar of all policymakers. A couple of other notable efforts to investigate the situation have been carried out by the University of Virginia and Dorel.

University of Virginia Updates Study
Naturally, the employer of the principle investigator of the 2007 Henary study, the University of Virginia (UVA) Center for Applied Biomechanics, was alerted to the JP Research findings several months ago.
Unfortunately, over the passage of time, the original researchers unintentionally lost the completed analyses from 2007, and the principle investigator has retired. Therefore, researchers currently at UVA undertook a re-evaluation of the data. Although their findings were not the same as those of JP Research, UVA did confirm that its analysis of the data does not support the value of riding rear facing to the extent originally concluded in the 2007 study. In particular, UVA agreed with JP Research that an error in weighting was a major flaw in the original study—the sample size simply wasn’t large enough to support statistical significance. As a result of this announcement, Injury Prevention, the journal that originally published the 2007 study, issued an “expression of concern” (see sidebar, left).
At press time, all stakeholders eagerly await the publication of this updated UVA research. SRN will report fully when it has been released.

Dorel Follow-Up Lab Testing
Dorel, the manufacturer that was the defendant in the lawsuit that originally inspired the updated research, says it has also done some follow-up investigation in a lab setting. It wanted to explore the possibility that interaction with the front seat might be a contributing factor to the study findings, a situation that is not simulated when using the current FMVSS 213 bench.
Using a 12-month-old test dummy in a Cosco APT convertible CR, Dorel conducted sled tests at an outside lab using a test setup like the one developed by Consumer Reports, which has a simulated front seatback in order to make tests in a lab setting more like a real vehicle situation. (For more about the Consumer Reports test setup, see SRN March/April 2014.)
Those tests produced higher (worse) head injury criteria scores for rear-facing mode than forward-facing mode, as well as worse results than similar tests of RF CRs on a bench without a simulated front seat. Dorel shared these findings in an online post in August.
As explained by Dorel, this lab testing was experimental only, and there may be many other factors involved. Nevertheless, it does suggest an important area for further research, as well as provide more evidence that an updated bench for regulatory test compliance is sorely needed.